State environmental regulators are gathering comments on a proposed air quality permit that would let Duke Energy reprocess and recycle coal ash stored at the Buck plant in Salisbury, North Carolina. The 30-day public comment period wraps up with a public hearing Tuesday night.
A 2016 state law requires Duke to reprocess coal ash at three of its 14 North Carolina coal plants. Much of the ash is too high in carbon to be re-used in concrete and other building products, so it has to be reburned to reduce the excess carbon.
To reburn the ash, Duke has hired SEFA Group of South Carolina to build incinerators at three plants - the Buck Plant, the H.F. Lee Plant in Wayne County and the Cape Fear Plant in Chatham County.
"Most of our ash has 8 to 12 percent carbon left in it. The concrete industry wants 2 to 3 percent," Duke spokeswoman Erin Culbert said. "This technology will allow us to remove that additional carbon, so we will have a highly desirable product for that market."
Because the coal ash will be burned, Duke needs approval to modify the air quality permits at the three plants. The Buck Plant is the first to go through the permitting process. The final decision is up to the state Division of Air Quality.
The reprocessing unit will include equipment to reduce emissions as the coal ash is burned, including a "scrubber" to remove sulfur dioxide, Duke said. The company said the burning process will comply with state and federal air-quality rules.
Coal ash is the residue left after burning coal. About 6.7 million tons of it are stored at the Buck Plant, which stopped using coal for electricity in 2013. (It now operates gas-fired units on the site.)
Duke eventually will be required to process a total of about 900,000 tons of coal ash a year at the three sites.
Duke already recycles about 40 percent of the coal ash it generates in North Carolina, Culbert said. It can't recycle more because of boiler designs and emissions control equipment that don't allow the carbon in coal to fully burn, she said.
Environmentalists have urged Duke to recycle more, and point to that fact that coal ash is imported to the state to satisfy demands for use in concrete and construction materials.
Culbert said the company hopes to begin construction in Salisbury in May. The reprocessing operation could open by the end of 2019. That would allow Duke to begin digging up coal ash from the Buck Plant's basins, where it's been stored for decades.
Duke said the recycling plant will employ more than 100 people during construction, and about a dozen people full-time once it's completed.
The public hearing on the Buck Plant permit begins Tuesday at 7 p.m. at North Rowan High School in Spencer, North Carolina. More information is on the Department of Environmental Quality website.